
7542 Group
Rev.3.02 Oct 31, 2006 Page 17 of 134
REJ03B0006-0302
Memory
Special function register (SFR) area
The SFR area in the zero page contains control registers such as
I/O ports and timers.
RAM
RAM is used for data storage and for a stack area of subroutine
calls and interrupts.
ROM
The first 128 bytes and the last 2 bytes of ROM are reserved for
device testing and the rest is a user area for storing programs.
The reserved ROM area can program/erase in the flash memory
version.
Interrupt vector area
The interrupt vector area contains reset and interrupt vectors.
Zero page
The 256 bytes from addresses 0000
16
to 00FF
16
are called the
zero page area. The internal RAM and the special function regis-
ters (SFR) are allocated to this area.
The zero page addressing mode can be used to specify memory
and register addresses in the zero page area. Access to this area
with only 2 bytes is possible in the zero page addressing mode.
Special page
The 256 bytes from addresses FF00
16
to FFFF
16
are called the
special page area. The special page addressing mode can be
used to specify memory addresses in the special page area. Ac-
cess to this area with only 2 bytes is possible in the special page
addressing mode.
Fig. 15 Memory map diagram
0100
16
0000
16
0040
16
0440
16
FF00
16
FFDC
16
FFFE
16
FFFF
16
384
512
1024
XXXX
16
01BF
16
023F
16
043F
16
8192
16384
32768
E000
16
C000
16
8000
16
E080
16
C080
16
8080
16
YYYY
16
ZZZZ
16
RAM
ROM
Reserved area
SFR area
Not used
Interrupt vector area
ROM area
Reserved ROM area
(128 bytes)
Zero page
Special page
RAM area
RAM capacity
(bytes)
address
XXXX
16
ROM capacity
(bytes)
address
YYYY
16
Reserved ROM area
address
ZZZZ
16
Not used
SFR area (Note 1)
0FE0
16
0FFF
16
Notes 1: Only flash memory version has this SFR area.
2: The reserved ROM area can program/erase in the flash memory version.
Note the difference of the mask version.